Control scheme for coordinating variable capacity components of a refrigerant system

Abstract

A refrigerant system adjusts, in a coordinated prioritized manner, the variable capacities of a compressor, evaporator fan and a condenser fan to minimize the system's overall power consumption while maintaining a comfort zone within a target comfort range. The target comfort range is defined by desired temperature and humidity limits. When the comfort zone is within the target comfort range, the system periodically attempts to reduce the compressor capacity. If the attempt succeeds, the evaporator fan capacity is then minimized. The condenser fan capacity can also be minimized provided the refrigerant system can maintain at least a minimum saturated suction temperature of the refrigerant flowing from the condenser to the compressor.

Description

FIELD OF THE INVENTION[0001]The subject invention generally pertains to refrigerant systems and more specifically to a control scheme for adjusting and coordinating the variable capacities of certain system components.BACKGROUND OF RELATED ART[0002]To meet the varying cooling and / or dehumidifying load of a comfort zone, some HVAC refrigerant systems might include a system component of adjustable capacity. Examples of adjustable capacity components include compressors, indoor evaporator fans and outdoor condenser fans.[0003]U.S. Pat. No. 5,303,561 discloses adjusting the indoor fan speed to meet the latent cooling needs of a comfort zone. U.S. Pat. No. 4,590,772 suggests varying the draft volume to a condenser based on the refrigerant pressure therein. U.S. Pat. No. 5,062,276 discloses a refrigerant system where the fan speed is varied linearly with compressor speed, and their speed relationship is altered in response to the need for dehumidification. U.S. Pat. Nos. 5,305,822; 5,345,...

AI Technical Summary

Benefits of technology

[0006]It is an object of the invention to provide a refrigerant system that can adjust in a coordinated manner the variable capacities of a compressor system, an evaporator fan system and a condenser fan system.

[0007]Another object of some embodiments is to provide a control scheme that minimizes the power consumption of a refrigerant system that includes multiple variable capacity components.

[0008]Another object of some embodiments is to minimize the capacity of a refrigerant system in a prioritized order with the compressor system being first, the evaporator fan system being second, and the condenser fan system being third.

[0010]Another object of some embodiments is to minimize the power consumption of a refrigerant system while maintaining a comfort zone within a target comfort range and maintaining at least a minimum saturated suction temperature of refrigerant leaving the system's condenser.

Problems solved by technology

Although adjusting the capacity of a single component might be relatively straightforward, it can be challenging to control a refrigerant system that includes more than one component of adjustable capacity because varying the capacity of one component can affect the performance of another.

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